Many vehicles are equipped with information systems that include a gauge or read out in an instrument panel or elsewhere in a passenger compartment of a vehicle that presents a driver and/or a vehicle occupant with information about the vehicle's performance. For example, many information systems provide information such as the distance, in miles and/or hours, of a recent or current trip and the number of miles that the vehicle can travel on the fuel remaining in the vehicle's fuel tank. Another item of information commonly presented to the driver of the vehicle is the vehicle's instantaneous fuel economy. The instantaneous fuel economy is a reflection of the gas consumption that the vehicle is achieving on a moment to moment basis. It is commonly measured in miles per gallon in the United States and in liters per 100 kilometers in Europe and it permits a driver to correlate his/her driving habits with his/her vehicle's fuel economy.
The instantaneous fuel economy has historically been calculated by using information collected by the vehicle's odometer and a fuel sensor. The odometer measures how far the vehicle has traveled and the fuel sensor measures, among other things, how much fuel has been consumed by the vehicle's internal combustion engine. Conventionally, in the United States, a vehicle's instantaneous fuel economy has been determined by measuring the distance that the vehicle has traveled during a period of time (e.g. the preceding two seconds), by measuring how much fuel the internal combustion engine consumed during that same period of time, and then dividing the distance by the amount of fuel consumed. In Europe, the fuel consumed is divided by the distance traveled.
While conventional systems and methods for determining instantaneous fuel economy are adequate, there is room for improvement. The data measurements utilized by conventional systems and methods look backward in time and therefore incorporate a time lag in the calculation of the instantaneous fuel economy. For example, if the instantaneous fuel economy is calculated based on the distance traveled during the preceding two seconds and the amount of fuel consumed during the preceding two seconds, then there will be at least a two second time lag before the instantaneous fuel economy can be presented to the driver because the information system is collecting data from the various sensors.
Additionally, conventional instantaneous fuel economy measuring systems have been known to show dramatic fluctuations in fuel economy during transitional stages such as when a driver lifts his/her foot from the gas pedal to coast, change gears, or to apply the brakes. During such periods when the gas pedal has been released and the vehicle is coasting, the distance traveled by the vehicle will not differ significantly from the preceding steady-state condition, but the fuel consumption will instantly drop precipitously. Because fuel consumption is the denominator in the equation for calculating instantaneous fuel economy, when the fuel consumption gets very small, the instantaneous fuel economy appears to get unrealistically large, and it does so very quickly.
Because of the time lag, the rapid fluctuations in instantaneous fuel economy, and the magnitude of such fluctuations associated with conventional systems and methods for determining instantaneous fuel economy, it is desirable to provide a system and method that addresses these concerns. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.